1. Field of the Invention
This invention concerns a fuzzy inference device.
2. Background of the Prior Art
Fuzzy inference is well known as a method by which the information amount of a phenomenon, which was used to arrive at an inference, can be used to correct or change the conclusion arrived at by the inference. (See, for example, Zhang Hongmin, "An Expert System with Thinking in Images," Preprints of the Second IFSA Congress, Tokyo, July 20-25, 1987, p. 765)
The fuzzy inference method is used to increase the discriminatory capacity of inferences. For each phenomenon, the information amount of that phenomenon (i.e., the capacity of the phenomenon possesses for the discrimination of its information) is determined using a membership function corresponding to each conclusion which may be drawn for that phenomenon. The inference (i.e., the possibility that a conclusion can be drawn) is corrected or changed (by finding the product of the possibility and the information amount) using the information amount of the phenomenon which led to that conclusion.
However, when a number of phenomena are related with respect to a single conclusion, the above inference scheme is unable to reflect their relationship in the inference result. For example, in the case in which a conclusion can be drawn when two phenomena have both occurred (i.e., two phenomena conjoined by AND), a correct inference cannot be made.
Additionally, in existing fuzzy inference schemes, it is assumed that the membership functions for phenomena have a single peak (single-humped function). These schemes cannot handle membership functions with two and three or more peaks in the range of variables, which are known as double-humped and multi-humped functions.
Nor can they handle the knowledge that various discrete phenomena relating to a single conclusion may be conjoined by OR or by AND.